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Phillip Donald Fawell

Phillip Donald Fawell
The Commonwealth Scientific and Industrial Research Organisation (CSIRO), Perth Australia · Mineral Resources

Doctor of Philosophy

About

94
Publications
19,139
Reads
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2,162
Citations
Introduction
I currently lead the CSIRO Mineral Resources "Hydrometallurgy Innovation" team, with my main research interests in aggregate/particle characterisation and flocculation mechanisms in feedwell and tailings treatment processes. I had a major role in the AMIRA P266 "Improving Thickener Technology" projects (1993-2016), in latter stages leading all flocculation and technology transfer aspects. P266 outputs have since been captured in flocculation/thickening workshops around the world.
Additional affiliations
April 1993 - present
The Commonwealth Scientific and Industrial Research Organisation
Position
  • Researcher
Description
  • Initially appointed to examine flocculant characterisation through the Parker Centre for Hydrometallurgy, later involved in all aspects of the flocculation process, including aggregate characterisation and thickener feedwell optimisation.
April 1991 - March 1993
Defence Science and Technology Group (DST)
Position
  • PostDoc Position
Description
  • GIRD funded program to examine the toughness and fire-resistance of glass-reinforced phenolic composite
January 1989 - February 1991
CSIRO Mineral Products
Position
  • PostDoc Position
Description
  • Examining poly(diallylamine) composites as potential substitutes for activated carbon in the concentration and purification of gold solutions
Education
February 1985 - January 1989
Murdoch University
Field of study
  • PhD Chemistry (organic electrochemistry)
February 1984 - December 1984
Murdoch University
Field of study
  • Honours (Chemistry
February 1981 - November 1983
University of Western Australia
Field of study
  • Bachelor of Science (Organic Chemistry/Physical and Inorganic Chemistry)

Publications

Publications (94)
Article
Full-text available
In areas where access to water for mineral processing is limited, the direct use of seawater in processing has been considered as an alternative to the expense of its desalination. However, efficient flotation of copper sulfides from non-valuable phases is best achieved at a pH > 10.5, and raising the pH of seawater leads to magnesium precipitates...
Article
As the expectations for more consistent and higher density thickened and paste tailings in the minerals industry increase, so do the demands on flocculation performance within gravity thickeners. Low solids feed suspensions are delivered at a high velocity to center feedwells, which not only serve to dissipate the feed’s momentum and evenly distrib...
Article
Mineral processing produces large volumes of dilute tailings that are flocculated and thickened, returning water to the process. The drive towards more sustainable processing has seen seawater considered to replace fresh water usage and an increased focus on how flocculation conditions can influence the fractal-like aggregates formed. The fragility...
Conference Paper
The use of seawater, hypersaline or other low-quality water supplies in mineral processing operations has strong benefits in places like Chile and Australia, not just economically but in ensuring social license to operate. Despite this commercial application, the effect of dissolved salts on tailings flocculation is not yet fully understood. This p...
Article
Full-text available
Post-thickener polymer addition to initiate rapid tailings dewatering has gained considerable interest for tailings storage facility (TSF) management. However, the highly viscous and non-Newtonian rheology of dense suspensions presents unique challenges for mixing with polymer solutions. Such mixing is highly inefficient, often resulting in polymer...
Article
In areas where access to water of good quality is limited, the use of seawater in mineral processing can be an option. However, the dewatering of waste tailings is adversely affected, particularly when this follows processing at higher pH. The flocculation response of a synthetic clay-based tailings in seawater to different pH conditions was examin...
Article
The presence of clays can make dewatering of tailings from mineral processing challenging. This review focuses on the interaction of clays in tailings under different conditions, including the impact of high salinity. The surface chemistry and aggregation behaviour of clays in suspension are first discussed, and this is then extended to clay aggreg...
Article
Aggregation within particle suspensions is often sought to enhance settling. Aggregate settling velocity and density predictions are directly related to the drag coefficient. Despite extensive studies on aggregate drag forces, there remains a lack of explicit correlations suitable across a range of properties and flow conditions; most employ implic...
Article
The flocculation efficiency of polyelectrolytes in high ionic strength environment is often affected and reduced due to shielding of the active ionizable functional groups, as well as changes in the surface chemistry of the solid slurry. To address this problem, a series of well-defined novel ABA triblock copolymers were employed for the flocculati...
Article
In gravity thickening, higher levels of fine particles within the feed slurry typically lead to reduced flocculation performance relative to that achieved at the optimal solids concentration and flocculant dosage. Grinding is applied prior to separation processes (e.g. flotation, leaching) to liberate valuable material, and the higher grinding requ...
Conference Paper
For over 25 years, the AMIRA P266 “Improving Thickener Technology” series of projects sought to advance fundamental understanding of all aspects of gravity thickening towards achieving better operational performance. Detailed studies of flocculation were complemented with mathematical and computational modelling, as well as both pilot and full-scal...
Article
The shear sensitivity of fragile, low-density aggregates formed in particle suspensions by polymer-bridging flocculation makes characterisation methods needing sampling or dilution problematic. Focused beam reflectance measurement (FBRM) probes can readily monitor such structures in real-time, but interpretation of resulting chord length data can b...
Article
Full-text available
Complicated geometrical objects like aggregate clusters can be characterised by a simple parameter: the fractal dimension. There are many ways to measure this fractal dimension. For most methods, it is found by the exponent of a relationship between an intrinsic value, such as mass or area, to a characteristic value, such as bulk aggregate length....
Article
In seeking to gain insights on the performance of long chain water-soluble polymer flocculants when conducting mineral processing in highly saline liquors, molecular dynamic simulation was used to study the effect of NaCl concentration on the conformation of an anionic polyelectrolyte and its adsorption on a quartz surface at pH values above its is...
Conference Paper
The need to reduce fresh water consumption has pushed many Chilean mining companies to utilize seawater obtained from distant locations. At the same time, increasing amounts of fine particles in copper tailings raise new operational challenges, in particular, the thickening and transport of tailings featuring significant fine fractions, which are p...
Article
Aqueous solutions (∼0.01–0.2%) of long chain polymers are used during gravity thickening to aggregate particle suspensions. These polymers are often dosed into turbulent flow through submerged pipes (sparges) to maximise their distribution. At high concentrations, these viscoelastic solutions mix poorly with surrounding flows unless highly diluted....
Article
The unique chemical and physical properties of oil sands tailings require the development of new classes of polymer flocculants to achieve efficient flocculation and dewatering. Fast and direct performance measurements of flocculation and dewatering efficiency are essential for the development of new polymer flocculants. The microscopic characteriz...
Conference Paper
Anionic copolymers have been used to enhance the dewatering and strength development properties of a wide range of tailings substrates around the mining world for at least two decades. The evaluation and selection of polymer treatment candidates for field application is often based on results obtained from a series of screening experiments to satis...
Conference Paper
Tailings rehabilitation, using soil-like properties with chemical and physical stability, can be influenced by surface forces on a particle scale and microstructure. Non-homogeneous structures, manifesting as particle aggregation, alter the permeability/porosity and improve the balance of aerated and water-filled pores that then favours plant growt...
Article
There are numerous models of sedimentation in fine particle suspensions, derived from or validated with physical measurements. Such models could be applied to optimise and control gravity thickeners used for solid-liquid separation in mineral processing. However, these applications rely upon particle bridging by high molecular weight polymers to fo...
Article
Unit operations used to achieve solid-liquid separation for fine particle suspensions rely upon efficient aggregate formation. There is considerable potential for predictions from population balance models describing particle aggregation to help optimise full-scale processes. The vast majority of studies in this area make use of the classical coagu...
Article
The influence of applied mixing (intensity and duration), solids concentration, and liquor chemistry on the molecular weight (MW) response of seven anionic (30%) polyacrylamides was investigated in the flocculation of standard kaolin slurry at pH 8. Continuous flocculation was achieved in a Couette mixing device (CSIRO Shear Vessel) with a vertical...
Chapter
Solid–Liquid Separation Techniques Used and the Relationship to Particle Size Hydrometallurgical processing of minerals invariably involves at least one stage of solid–liquid separation. This can be for a variety of purposes, ranging from the clarification of liquors through to high-solids slurry dewatering, usually with the needs of downstream pro...
Presentation
Hydrometallurgical processing of minerals invariably involves at least one stage of solid-liquid separation, with purposes ranging from liquor clarification through to high solids suspension dewatering, usually having downstream processing needs in mind. Gravity thickeners are employed to treat dilute suspensions when high volumetric throughputs ar...
Conference Paper
Polymer activity in dewatering applications is well known to be affected by molecular weight (MW). In practice the polymer’s solution dimensions - both chain length and conformation in solution - has the greatest impact on its capacity for particle bridging. Similar polymer chemistries to those applied within individual thickener operations are oft...
Conference Paper
Full-text available
Minerals processing and hydrometallurgy are mature industries; however, despite many years of plant design and operational experience we continue to design and/or operate sub-optimal plants. At a time when most companies have small margins between production costs and product prices this is no longer tolerable. Feed variation (among other factors)...
Chapter
Sodalite represents the main desilication product (DSP) phase formed from reactive silica during alkaline digestion of bauxite in the Bayer Process. Previous studies into DSP effects on bauxite residue flocculation have focused on flocculant selection or digestion optimisation, not answering a fundamental question: does DSP coat the residue and the...
Conference Paper
Full-text available
Bluff body shapes are used to promote better heat and mass transfer in various industrial flow situations, flow past them serving to enhance turbulence and thereby promote mixing, primarily due to the vortex shedding created. In this paper, the turbulent mixing fields for flow past a square sparge jet is investigated both experimentally and numeric...
Conference Paper
Small‐scale cylinder or jar tests are routinely applied to establish the impact of polymer reagents that induce aggregation in mineral systems. Despite their value, such tests are often done poorly or under too narrow a range of conditions, which can lead to trends being either missed or wrongly interpreted. A number of common errors are discussed,...
Chapter
This chapter deals with the reagents that are applied in fine particle slurry systems to enhance dewatering and handling. There are many publications that deal with this subject, but the following focuses on tailings applications, which can be quite distinct from other systems in their behaviour and requirements. Discussions on such reagents are us...
Chapter
This section on thickening reviews the art of sedimentation and the practicality of settling solids in a thickener to produce thickened tailings or paste. The various types and styles of thickeners are discussed, illustrating the makeup of each type. The use of chemicals to enhance thickening or the settling of solids is addressed in Chapter 6. The...
Article
CFD modelling offers powerful simulation capability, but only provides information for a given design and set of process conditions. While it allows comparison between different outcomes, CFD results alone do not provide an optimised outcome. In many design problems, thousands of function evaluations may be required to undertake an optimisation stu...
Article
The performance of a thickener feedwell depends not only on its ability to generate large-sized aggregates from feed particles but also on aggregate density. The performance of the flocculant BASF Rheomax® DR 1050 has been previously compared to a conventional anionic flocculant in turbulent pipe flocculation of mineral suspension, suggesting that...
Conference Paper
Minerals processing and hydrometallurgy are mature industries, however, despite our combined many years of plant design and operational experience we continue to operate sub-optimal plants. At a time when most operators have small margins between production costs and achieved product prices this is no longer tolerable. Feed variation amongst many o...
Conference Paper
The use of post-thickener polymer addition to initiate rapid dewatering from treated slurries has gained considerable interest recently for tailings storage facility (TSF) management. The mixing of high-density thickener underflows and polymer solutions, however, presents unique challenges due to the highly viscous and non-Newtonian rheology of the...
Article
Focused beam reflectance measurement (FBRM), where a scanning laser focused through a sapphire window measures real-time reflected chord distributions without solids dilution, is attractive for characterizing flocculation performance. An enhanced measurement principle in new FBRM instruments has implications for flocculation studies, demonstrated u...
Article
The polymer-bridging flocculation processes that take place in hydrometallurgical thickening are very much affected by the solid concentration at the point of flocculant dosing, with the optimum concentrations maximising settling flux often well below that of the thickener feed. This is a consequence of the open, low density aggregate structures fo...
Conference Paper
Achieving adequate solids dilution prior to flocculation in thickeners can be problematic, and hence flocculants producing denser aggregates may offer practical advantages. Plant-based studies suggest Rheomax® DR 1050 (BASF) has such potential, although quantification of this is difficult to achieve. Flocculation kinetics characterisation in turbul...
Conference Paper
Sodalite represents the main desilication product (DSP) phase formed from reactive silica during alkaline digestion of bauxite in the Bayer Process. Previous studies into DSP effects on bauxite residue flocculation have focused on flocculant selection or digestion optimisation, not answering a fundamental question: does DSP coat the residue and the...
Article
Sodalite represents the main desilication product (DSP) phase formed from reactive silica during alkaline digestion of bauxite in the Bayer Process. Previous studies into DSP effects on bauxite residue flocculation have focused on flocculant selection or digestion optimisation, not answering a fundamental question: does DSP coat the residue and the...
Conference Paper
Full-text available
Computational Fluid Dynamics (CFD) modelling offers powerful simulation capability, but only provides information for a given design and set of process conditions. While it allows comparison between different outcomes, CFD results alone do not provide an optimised outcome. The computational cost associated with the use of high-fidelity CFD models p...
Conference Paper
The performance of a thickener feedwell depends not only on its ability to generate large-sized aggregates from feed particles but also on aggregate density. The performance of the flocculant BASF Rheomax® 1050 has been previously compared to a conventional anionic flocculant in pipe reactor experiments, suggesting that the Rheomax product can gene...
Article
The conformation of acrylamide/acrylate copolymers' aqueous solutions is known to be affected by the presence of cations to varying degrees. Such effects are expected to be reflected in the flocculation activity of the polymer solutions, but the published literature in this area is far from convincing, particularly on the influence of divalent cati...
Article
The feedwell performance in gravity thickeners and clarifiers relies on the efficient mixing between solid particles and flocculant to achieve effective flocculation, as well as energy dissipation of the incoming feed stream. A population balance-computational fluid dynamics (PB-CFD) model has been developed and validated to provide new insights in...
Conference Paper
Full-text available
The measurement of fluid flow patterns within pilot or large scale process vessels is an important step in understanding their base-line behaviour and optimising operating performance. Traditionally,velocity measurements within such vessels could not be readily carried out using laser based techniques due to their size and often, due to the non-tra...
Article
An investigation of the simultaneous precipitation of iron oxide and silica species from acidic solutions was conducted, simulating the paragoethite process, an iron-removal stage employed in zinc hydrometallurgy. Laboratory-based continuous crystallisation experiments were carried out under the primary conditions employed in industry, with pH (at...
Conference Paper
The pre-desilication step within the Bayer Process seeks to transform reactive silica in bauxite into desilication product (DSP) prior to digestion, thereby reducing post-digestion precipitation and scaling. The precipitated DSP is removed with the other residue phases in the primary settling stage. While the proportion of DSP within the residue ca...
Conference Paper
Full-text available
Advanced Computational Fluid Dynamics (CFD) modelling techniques are well suited for examining suspension flow patterns within feedwells and thickeners from which improved design options can be developed and evaluated. However, the confidence to rely upon recommendations based upon CFD requires model validation, something that is not readily achiev...
Article
The effect of the presence of soluble silicates on ferrihydrite precipitation and some properties of the products formed in co-precipitation of ferrihydrite and silica have been investigated. The co-precipitates were formed using a continuous crystallisation process in which a combined iron/silicon feed solution was reacted with sodium hydroxide at...
Article
Solid–liquid separation of tailings slurries in gravity thickeners relies on the efficient mixing of slurry and dilute polymer flocculant solutions within the feedwell. Computational fluid dynamics (CFD) can provide predictions of solids distribution, liquor velocity and shear rate within a feedwell, and with the incorporation of an adsorption mode...
Conference Paper
The AMIRA P266 'Improving Thickener Technology' series of projects has sought to provide a firm scientific basis for feedwell and thickener design, a requirement as pressures on water usage in the minerals industry increase. While advanced computational fluid dynamics modelling of feedwell processes has generated the most obvious and successful app...
Conference Paper
Full-text available
As the expectations for more consistent and higher density thickened and paste tailings increase, so do the demands on thickener performance. Over the last 20 years, the AMIRA P266 “Improving Thickener Technology” series of projects, have significantly advanced the understanding of thickening by combining fundamental investigations of flocculation,...
Article
Batch flocculation tests in cylinders (jars) or stirred vessels suffer from poor control over the reaction time and involve broad shear rate distributions. The use of a linear pipe reactor provides continuous turbulent mixing of flocculant and slurry at well-defined mean shear rates. Combined with in-line, real-time monitoring of the aggregation st...
Article
The flocculation activity achieved with aqueous solutions of polyacrylamide and acrylamide/acrylate copolymers is shown to be highly dependent upon the solution age. Continuous flocculation with a standard kaolin slurry in a Couette mixing device, giving settling rate and in-line chord length distributions, allows the comparison of different floccu...
Article
The adsorption of polymers is typically characterised by segments of adsorbed “trains” and unadsorbed “loops” and “tails”. Attenuated total reflectance infrared spectroscopy is thus an ideal means of studying this process in situ. In this study the adsorption of long chain polyacrylates onto hematite at pH 2 and 13 has been examined using a single...
Article
The initial hindered settling velocities of flocculated calcite suspensions have been related to the mean aggregate sizes and solid fraction under a range of flocculation conditions that are similar to those occurring within a mineral processing thickener. Calcite particles were flocculated in turbulent pipe flow and the aggregates sized with an in...
Article
A population balance (PB) model is used to describe the aggregation/breakage kinetics of calcite flocculation in turbulent pipe flow. The model describes simultaneous aggregation and breakage, and accounts for likely process variables: fluid shear, flocculant dosage, primary particle size and solid fraction, using four fitted parameters. Particle c...
Conference Paper
Full-text available
Feedwell performance and the resultant aggregates strongly influence thickener underflow properties and the opportunity for paste formation. The permeability (related to hindered settling) and compressibility are key measures affecting the dewatering of flocculated slurries during solid-liquid separation. A sedimentation model was developed for the...
Article
The kinetics of aggregation/breakage of calcite particles flocculated with a high-molecular-weight polymer flocculant has been studied in turbulent pipe flow. The mean flocculation residence time was varied by changing the length of pipe between the flocculant injection point and the in-stream particle-sizing probe (Lasentec FBRM). A variety of pip...
Article
FTIR-ATR was used to examine in situ the interaction of polyacrylate and hematite at pH 13. Static light scattering and mobility measurements were used to assess solution polyacrylate dimensions and hematite surface charge, respectively. Polyacrylate adsorption occurred only with the addition of electrolyte (e.g., NaCl), and it was found that exces...
Article
A linear pipe reactor (LPR) system was used to study the flocculation of mineral suspensions with commercial flocculants under a variety of operating conditions. Incorporation of a Lasentec focused beam reflectance measurement (FBRM) probe into the system provided real-time, in situ characterisation of the aggregate dimensions during the flocculati...
Conference Paper
Full-text available
Research projects towards developing a sound understanding of the factors controlling the performance of gravity thickeners have been conducted by the AJ Parker Cooperative Research Centre for Hydrometallurgy since 1988 through AMIRA International. The current phase of this work, the three year P266D “Improving Thickener Technology” project, has 27...
Article
The adsorption of water-soluble polymers (e.g., flocculants, coagulants) onto mineral particles is typically characterized by “trains” of adsorbed polymer segments with “loops” and “tails” of unadsorbed polymer segments that extend into the solution. Ex situ spectroscopic studies carried out in the past have been complicated by the way in which the...
Article
Aqueous solutions of high molecular weight polyacrylamides used to flocculate mineral slurries undergo time-based changes in their properties. Previous studies of the impact of ageing on flocculation performance have focused on time-scales of weeks or months, which has little relevance to industrial practice. In this study, ageing times from 1 h to...
Conference Paper
For the majority of tailing substrates, flocculant adsorption proceeds through the interaction of amide functionalities with neutral surface species. For anionic copolymer flocculants, the acrylate component of the polymer does not directly participate in adsorption, only serving to provide chain extension in solution. The flocculation of bauxite r...
Article
The Lasentec focused beam reflectance measurement (FBRM) probe provides in situ particle characterisation over a wide range of suspension concentrations. This is a significant advantage over conventional instruments that require sampling and dilution. However, FBRM gives a chord distribution, rather than a conventional diameter distribution. Both t...
Article
The Lasentec focused beam reflectance measurement (FBRM) probe provides in situ particle characterisation over a wide range of suspension concentrations. This is a significant advantage over conventional instruments that require sampling and dilution. However, FBRM gives a chord distribution, rather than a conventional diameter distribution. Both t...
Chapter
El Centro de Investigación Cooperativa A.J. Parker para la Hidrometalurgia ha desarrollado proyectos de optimizacion de la tecnologia de espesadores desde 1988 a través de la Asociación Australiana para la Investigación en las Industrias Mineras (AMAIRA) con el apoyo de 25 empresas australianas y extranjeras. Estos proyectos ha dodo como resultado...
Article
Research projects directed towards ‘Improving Thickener Technology’ have been conducted by the AJ Parker Cooperative Research Centre for Hydrometallurgy since 1988 through the Australian Mineral Industries Research Association with support from 25 Australian and international mineral processing companies. These projects have resulted in the develop...
Article
The coupling of flow field-flow fractionation (flow FFF) and a multiangle laser light-scattering (MALLS) detector enables absolute measurements of weight-averaged molecular mass distributions for polymer solutions. The technique, applied recently to polyacrylamide (PAAm) standards, has been extended to commercial nonionic flocculants in an aqueous...
Conference Paper
Focused beam reflectance measurement (FBRM) may be used for in situ assessment of aggregate dimensions. FBRM was used in conjunction with the Shear Vessel, a tool used to characterise flocculation performance, in which an inner-rotating cylinder generates an annular (Couette) shear zone for continuous mixing. The mean weighted chord lengths from FB...
Conference Paper
Flow field-flow fractionation (FlowFFF) with multi-angle laser light scattering (MALLS) detection has been applied to the fractionation of polyacrylamide standards and commercial flocculant solutions. For standards, molecular mass distributions were achieved in under two hours, with a relationship observed between molecular mass and elution time. A...